If it’s in the Massachusetts rule-book, it’s there only ambiguously and only by implication:
To help reduce the levels of anxiety, you should do the following during a traffic stop.
• Don’t ignore the officer’s signal or pretend you didn’t see it.
• Turn on the appropriate turn signal and check your mirrors. Carefully and slowly move your vehicle completely to the side of the road. If the officer drives by and doesn’t stop, return to the travel lane when it is safe.
• Do not stop your vehicle in an intersection, in front of a driveway, or in a travel lane. If the officer directs you to pull over in a certain place, pull over where directed.
This is not permission to pull over only after the driver has judged that it is finally safe.
Cf. also: